1. Field of the Invention
The present invention relates to a glass run adapted to be mounted in a sash provided on a body or door of a vehicle.
2. Description of the Related Art
As shown in FIG. 29A, a glass run 61 has a main body portion 65 provided with a base portion 62 and a pair of side wall portions 63, 64 which extend from the base portion 62 and a pair of seal lips 66, 67 which extend from substantially distal ends of both the side wall portions 63, 64 toward an interior space of the main body portion 65. Then, as shown in FIG. 29B, the main body portion 65 is mounted in a sash S provided on a body or door of a vehicle, whereby an interior side or passenger compartment side and an exterior side of a door window glass G are sealed by the seal lips 66, 67, respectively.
In general, in the manufacture of glass runs 61, extruded portions are formed continuously by a known extrusion. Then, with distal end portions of extruded portions being set in a metal mold for molding a molded portion, a molded portion is molded so as to be continuously connected to end faces of the extruded portions. The molded portion corresponds mainly to a corner portion, where two extruded portions are connected to each other in such a state that a predetermined angle (for example, 90 degrees) is formed therebetween.
As shown in FIG. 29C, a mold unit 70 used for the connection molding of the molded portion is provided with a stationary mold 71, a plurality of movable molds 72 to 75 and a core mold 76. The core mold 76 is made up, in turn, of a core main body 77 for defining inner circumferential surfaces of the main body portion 65 and the seal lips 66, 67 of the glass run 61 and a holding portion 78 which protrudes from the core main body 77. In molding a molded portion, firstly, the core main body 77 is set in the mold unit 70 so as to be fitted therein in such a state that the respective molds 71 to 76 are opened, and extruded portions are mounted in the mold unit 70. Then, the respective molds 71 to 76 are disposed at predetermined positions and are then clamped together. At this point, a cavity 80 for molding a molded portion is defined by the respective molds 71 to 76. Then, unvulcanized rubber is injected and compacted into the cavity 80 via a gate or the like. Thereafter, the unvulcanized rubber is vulcanized, and the respective molds 71 to 76 are opened, whereby the core mold 76 and the vulcanized rubber are integrally removed from the mold unit 70. Then, the resulting molded portion is removed from the core mold 76, whereby a glass run 61 is obtained in which the molded portion and the extruded portions are made integral with each other.
Conventionally, as shown in FIG. 29A, both the extruded portions and the molded portion are molded in a state such that the pair of side wall portions 63, 64 are spread relative to the base portion 62 or are opened out outwardly around root portions thereof which are joined to the base portion 62 as base points. This is because in molding the molded portion, although the core main body 77 needs to be set in the mold unit 70 in order to define the inner circumferential surfaces of the main body portion 65 and the seal lips 66, 67, in the case of the mold unit 70 having the cavity 80 in which the seal lips 66, 67 are located close to each other, unless the molded portion is molded with the side wall portions 63, 64 being so opened out, a sufficient thickness W3 cannot be given to the holding portion 78 for holding the core main body 77.
As shown in FIG. 29B, in mounting the glass run 61 so molded with the side wall portions 63, 64 being opened out in the sash S, the side wall portions 63, 64 are both contracted from the opened-out state to a non-opened-out state. Namely, in a mounting state, the side wall portions 63, 64 are both moved inwardly, so that the main body portion 65 is shaped so as to have substantially a U-shaped cross section. As this occurs, without the door window glass G, distal end portions of both the seal lips 66, 67 are brought into abutment with each other.
In the aforesaid related art, when the molded portion is contracted so as to be mounted in the sash S, respective portions of the molded portion (the corner portion) do not deform uniformly, and the bending angle (and the radius of curvature and length of circumference) of the molded portion may be caused to change due to stress produced therein then. As this occurs, the whole shape of the glass run 61 is not allowed to follow the shape of the sash, leading to a risk that there occurs a mounting failure.
On the other hand, while it is considered possible to design the glass run 61 with the opened out side wall portions in the light of the change in the bending angle or the like, since it is not possible, in reality, to estimate what type of change occurs to what extent, a number of tries and errors have to be carried out repeatedly, thereby calling, as a result, for a remarkably large increase in man hours for design of such a glass run.
In addition to the aforesaid type of glass run, there is proposed a glass run in which a bellows-like extension portion is formed in a base portion of a molded portion so as to extend and contract in a direction traversing the interior and exterior of the vehicle, so that the extension portion, which is in an extended state before it is mounted in a sash, is contracted at the time of mounting so as to be fitted in the sash (for example, refer to Japanese Patent Publication No. JP-A-9-315161).
In the invention described in JP-A-9-315161, however, the extension portion is provided at a portion of the base portion which faces a door window glass, and there may be caused a risk that an end face of the door window glass is brought into abutment with the extension portion. Due to this, the door window glass is swung transversely inwards or outwards, leading a risk that the sliding positions of end faces of the door window glass along vertical side portions of the glass run become unstable and the abutment position of an end face of the glass run along an upper side portion of the glass run also becomes unstable, thereby calling, as a result, for a decrease in the sealing properties of the glass run. Furthermore, in the event that the end face of the door window glass is brought into abutment with the extension portion repeatedly, there may be caused a problem that the durability of the extension portion and hence the glass run is deteriorated.
In addition, when working to mount the glass run provided with the extension portions in the sash, an assembly worker has to sequentially fit respective portions of the glass run along the full length thereof in the sash while maintaining the extension portions in the contracted state, this eventually requiring lots of labor hours.
On top of this, from the viewpoint of improving the functionality of glass runs, in recent years, more functions are desired to be added thereto. In the event that the extension portion is provided, however, it has been difficult to provide additional functions such as a lip for reducing the collision noise produced when the door window glass is closed.
In addition, in molding the molded portion, in consideration of the injection pressure at which the unvulcanized rubber is injected into the cavity 80 via the gate or the like, not only the thickness W3 of the holding portion 78 described in the related art but also the holding portion of a core mold used for molding the molded portion of the glass run described in JP-A-9-315161 cannot be ensured as sufficient. For example, in the event that an injection pressure exceeding an estimated injection pressure is applied to the holding portion 78 from a side thereof, there may be caused a risk that the holding portion 78 is bent, whereby the shape of the cavity 80 is distorted. As a result, a glass run 61 of proper shape cannot be obtained, leading to a risk that the aforesaid various types of drawbacks are caused including the mounting failure and deterioration in the sealing properties of the glass run 61.